1,1′-bi-2-naphthol, a compound obtainable by dimerization of β-naphthol or its derivative, is useful for preparing an antiseptic compound or an asymmetric synthesis catalyst.
In addition, dimers of 2-hydroxynaphthalene-3-carboxylic acid and of 2-hydroxynaphthalene-6-caboxylic acid are useful as toning agents.
U.S. Pat. No. 3,278,610 discloses a method for preparing said dimer, which comprises dimerising β-naphthol in a solvent such as benzene in the presence of copper chloride, amine and oxygen.
J. Org. Chem. 1999, 64, 2264-2271 discloses a method for dimerizing β-naphthol or the like, which comprises oxidative coupling of p-naphthol, methyl 2-hydroxynaphthalene-3-carboxylate or the like in the presence of copper (I) chloride-tetramethylethylenediamine complex in dichloromethane, wherein copper (I) chloride and tetramethylethylenediamine are combined before the coupling reaction.
Conventional methods for preparing binaphthol derivatives require a solvent, such as benzene or dichloromethane, to dissolve β-naphthol or the like therein to facilitate the coupling reaction, and the solvent causes high cost. Further, the method of J. Org. Chem. 1999, 64, 2264-2271 is complicated because the method comprises the extra step of combining copper (I) chloride and tetramethylethylenediamine prior to the coupling reaction.